From: Simon Ser <contact@emersion.fr>
To: "André Almeida" <andrealmeid@igalia.com>
Cc: "Pekka Paalanen" <ppaalanen@gmail.com>,
dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
linux-kernel@vger.kernel.org, kernel-dev@igalia.com,
alexander.deucher@amd.com, contactshashanksharma@gmail.com,
amaranath.somalapuram@amd.com, christian.koenig@amd.com,
pierre-eric.pelloux-prayer@amd.com,
"Rob Clark" <robdclark@gmail.com>,
"Andrey Grodzovsky" <andrey.grodzovsky@amd.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Daniel Stone" <daniel@fooishbar.org>,
"'Marek Olšák'" <maraeo@gmail.com>,
"Dave Airlie" <airlied@gmail.com>,
"Pierre-Loup A . Griffais" <pgriffais@valvesoftware.com>
Subject: Re: [PATCH v3 0/2] drm: Add GPU reset sysfs
Date: Wed, 30 Nov 2022 15:34:00 +0000 [thread overview]
Message-ID: <9WiGqqLyo5VwAmb8qBPZAhUiq_ptdB-lNo5d6A42raXoJU8XPxojB_44bKkR8Tw82SdiiPz1lAKpe7HH9HlDA0fFpgcy6shNjTDxOfsadFE=@emersion.fr> (raw)
In-Reply-To: <2dbf222e-7694-ea5e-c35d-663011c16e84@igalia.com>
On Wednesday, November 30th, 2022 at 16:23, André Almeida <andrealmeid@igalia.com> wrote:
> On 11/28/22 06:30, Simon Ser wrote:
>
> > The PID is racy, the user-space daemon could end up killing an
> > unrelated process… Is there any way we could use a pidfd instead?
>
> Is the PID race condition something that really happens or rather
> something theoretical?
A PID race can happen in practice if many PIDs get spawned. On Linux
PIDs wrap around pretty quickly.
Note, even a sandboxed program inside its own PID namespace can trigger
the wrap-around.
> Anyway, I can't see how pidfd and uevent would work together. Since
> uevent it's kind of a broadcast and pidfd is an anon file, it wouldn't
> be possible to say to userspace which is the fd to be used giving that
> file descriptors are per process resources.
Yeah, I can see how this can be difficult to integrate with uevent.
> On the other hand, this interface could be converted to be an ioctl that
> userspace would block waiting for a reset notification, then the kernel
> could create a pidfd and give to the blocked process the right fd. We
> would probably need a queue to make sure no event is lost.
A blocking IOCTL wouldn't be very nice, you can't integrate that into
an event loop for instance…
next prev parent reply other threads:[~2022-11-30 15:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-25 17:52 [PATCH v3 0/2] drm: Add GPU reset sysfs André Almeida
2022-11-25 17:52 ` [PATCH v3 1/2] drm: Add GPU reset sysfs event André Almeida
2022-11-28 9:27 ` Pekka Paalanen
2022-11-29 14:07 ` Alex Deucher
2022-11-25 17:52 ` [PATCH v3 2/2] drm/amdgpu: Add work function for GPU reset event André Almeida
2022-11-28 9:25 ` [PATCH v3 0/2] drm: Add GPU reset sysfs Pekka Paalanen
2022-11-28 9:30 ` Simon Ser
2022-11-30 15:23 ` André Almeida
2022-11-30 15:34 ` Simon Ser [this message]
2022-11-30 11:11 ` Daniel Vetter
2022-12-08 4:53 ` Alex Deucher
2023-01-05 12:25 ` Daniel Vetter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='9WiGqqLyo5VwAmb8qBPZAhUiq_ptdB-lNo5d6A42raXoJU8XPxojB_44bKkR8Tw82SdiiPz1lAKpe7HH9HlDA0fFpgcy6shNjTDxOfsadFE=@emersion.fr' \
--to=contact@emersion.fr \
--cc=airlied@gmail.com \
--cc=alexander.deucher@amd.com \
--cc=amaranath.somalapuram@amd.com \
--cc=amd-gfx@lists.freedesktop.org \
--cc=andrealmeid@igalia.com \
--cc=andrey.grodzovsky@amd.com \
--cc=christian.koenig@amd.com \
--cc=contactshashanksharma@gmail.com \
--cc=daniel@ffwll.ch \
--cc=daniel@fooishbar.org \
--cc=dri-devel@lists.freedesktop.org \
--cc=kernel-dev@igalia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=maraeo@gmail.com \
--cc=pgriffais@valvesoftware.com \
--cc=pierre-eric.pelloux-prayer@amd.com \
--cc=ppaalanen@gmail.com \
--cc=robdclark@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).